To evaluate the immunological effects of occupational exposure to lead and organic solvents, we carried out the following studies and got those findings.1. We measured immunoglobulins, lymphocyte subpopulations and other lead-related indices in two male lead workers, to whom calcium disodium ethylenediamine tetraacetate (CaEDTA) was administrated three times a week. Significant increases in IgG, IgA, IgM, CD8+ and CD57+ cells in one worker and a significant increase in IgD in another after CaEDTA injection were found. There was a significant negative correlation between PbB and IgG in one worker. It is suggested that the immunological function such as antibody formation in lead workers might be improved by CaEDTA injection.2. We analyzed lymphocyte subpopulations in 29 male lead stearate workers and found a significant reduction of CD16+ natural killer (NK) cells in the high PbB group (【greater than or equal】20 μg/dl). There was significant negative correlation between the number of CD16+ cells and PbB. It is suggested that the CD16+ NK cell should be a major site of the effects of lead on lymphocyte subpopulations.3. We analyzed T cell subpopulations in 71 male lead stearate workers and found a significant reduction in the number of CD3+CD45RO+ (memory T) cells. There was a significant positive correlation between the percentage of CD3+CD45RA+ (naive T) cells and PbB. It is suggested that CD45RO+ memory T cells may be susceptible to the effects of lead on T cell subpopulations.4. We analyzed lymphocyte subpopulations in 16 male rotogravure printers workers exposed to toluene and found reductions in numbers of all NK cell subpopulations, CD4+CD45RA+ and CD8+ cells, an expansion in the number of B cells at the end of weekdays and their associations with blood toluene levels. It is suggested that numbers of those cells might be altered by the effects of toluene.